摘要
针对低开关频率下传统方法在求解多电平逆变器特定谐波消除(Selective harmonic elimination pulse width modulation,SHEPWM)的非线性方程组时存在初始值选取困难、非线性方程组转化复杂、容易得到局部最优解问题,提出一种新的求解方法。首先利用三角函数公式变换非线性方程组,其次通过设定约束条件将非线性方程组转化为线性方程组进行求解。以五电平U型逆变器(Modified packed U-cells,MPUC)为研究对象,将拓宽调制度的双波段SHEPWM控制方法与新方法结合得到调制度在[0,1.15]的精确解,并将新方法求解与智能算法求解进行对比。对比显示新方法在低调制度下具有更好的总谐波畸变率(Total harmonic distortion,THD)。最后以仿真和试验证明新方法可以有效消除五电平逆变器的五次谐波。
When solving the nonlinear equations of specific harmonic elimination of multi-level inverter,the traditional method at low switching frequency has the problems of difficult selection of initial values,the complex transformation of nonlinear equations,and it is easy to obtain local optimal solutions.A new harmonic elimination method for multilevel inverter is proposed.Firstly,the nonlinear equations are transformed by using the trigonometric function formula,and then constraint condition are assumed to transform the nonlinear equations into linear equations for solving.Taking five-level modified packed U-cells(MPUC)as the research object,exact solutions in[0,1.15]are obtained by combining the double-band SHEPWM control method with the new method.The new method is compared with the intelligent algorithm.The comparison shows that the new method has better total harmonic distortion rate(THD)under low modulation.Finally,simulation and experiment show that the new method can effectively eliminate the fifth harmonic of the five-level inverter.
作者
李国华
苑朝鸣
LI Guohua;YUAN Zhaoming(Faculty of Electrical and Control Engineering,Liaoning Technical University,Huludao 125105)
出处
《电气工程学报》
CSCD
2023年第4期171-178,共8页
Journal of Electrical Engineering
基金
国家自然科学基金(51307076)
辽宁省科技厅博士科研启动计划(2021-BS-273)资助项目。
关键词
低开关频率
特定谐波消除
非线性方程组
MPUC逆变器
三角函数
线性方程组
Low switching frequency
selective harmonic elimination
nonlinear equations
MPUC inverter
trigonometric function
linear equations
